SEOUL - The president of China, which has grown increasingly frustrated over North Korea's pursuit of nuclear weapons, congratulated its leader, Kim Jong Un, on his promotion to chairman of the ruling party, North Korean state media said on Tuesday.
Kim, 33, the third-generation leader of isolated North Korea, added the title of chairman of the Workers' Party of Korea (WPK) on Monday, the closing day of the country's first ruling party congress in 36 years.
"I wish the Korean people fresh success in carrying out the cause of socialism under the leadership of the WPK headed by Chairman Kim Jong Un," Chinese President Xi Jinping told Kim in a message, North Korea's KCNA news agency said.
"We will make efforts together with the DPRK side to bring happiness to the two countries and their peoples and contribute to peace, stability and development in this region by steadily developing the Sino-DPRK friendship and co-operation." DPRK stands for Democratic People's Republic of Korea, the North's official name.
China's official Xinhua news agency cited Xi as saying that friendship between the two countries "was personally forged and carefully fostered by the two countries' leaderships of the older generation". "The traditional friendship is a treasure of both sides," Xi added.
There was no direct mention of North Korea's nuclear programme. North Korea said it would strengthen its defensive nuclear weapons capability, a decision adopted in defiance of UN resolutions.
China, North Korea's chief ally and main trading partner, backed tough UN Security Council sanctions against North Korea in March following the North's fourth nuclear test in January.